1. Field of the Invention
The present invention relates to a switch device, and more particularly to an improved a switch device having an indicator for indicating an operation amount of a switch.
2. Description of Related Art
Switch devices are conventionally used for setting an amount of control for various devices. For example, rotary volume switches and sliding switches are widely used. FIG. 6 shows a mixer device 100 used for recording, which is one example of an operation panel in which a large number of such switch devices are arranged. In such a mixer device 100, because it is necessary to visually recognize the operation amount of many switch devices instantaneously, an indicator 102 capable of showing visually noticeable change is often provided. In particular, for a mixer device 100 often used in a dimly-lighted room, a light emitting indicators 102 which allows quick judgment of the operation amount (the amount or level to which a switch device has been operated, moved, or adjusted) are widely used, because such indicators are easier to recognize and costs less to manufacture than number display type switches, for example.
As an example, FIGS. 7A and 7B illustrate a switch structure including a rotary volume switch (hereinafter simply referred to simply as a xe2x80x9cswitchxe2x80x9d) 104 and an indicator 102 including a plurality of LEDs 102a arranged in a circle around the switch. More specifically, FIG. 7A shows an example in which the position of a lit LED 102a is sequentially moved in accordance with the operation amount of an operation knob (hereinafter simply referred to as a xe2x80x9cknobxe2x80x9d) 104a of the switch 104. The operation amount of the knob 104a corresponds to an operation amount of the switch 104. In the example shown in FIG. 7A, an LED 102at (at the apex position) is lit in accordance with the amount of operation of the knob 104a. FIG. 7B shows another example in which a single LED 102a indicating a special condition of the switch 104, such as a point which requires particular attention including a predetermined threshold or the like of the switch 104 (hereinafter, such a point will be referred to as an xe2x80x9cattention pointxe2x80x9d), continuously lights up, whereas another LED 102a sequentially lights up in accordance with the operation amount of the knob 104a. In the example shown in FIG. 7B, the LED 102at (at the apex position), which serves as an attention point, is continuously lit to indicate the threshold value, and the LED 102ap next to the LED 102at on the right side also lights up for indicating the operation amount of the knob 104a. 
Similar type of switch devices which are provided with such an indicator are also used in, for example, an operation panel in the cockpit of an air plane and operation panels for various devices installed in a vehicle. In any of these cases, it is necessary to quickly and easily recognize visually the operation amount of the switch device.
While mixer devices 100 shown in FIG. 6 come in a wide range of sizes, a typical device may have a width of 1 m or more and a depth of approximately 0.6 m. An operator operates the mixer device 100 while he/she is sitting or standing at approximately the midpoint in front of the mixer device 100. This causes a problem that for a switch 104 having a knob 104a with a predetermined height as shown in FIGS. 7A and 7B, part of the indicator 102 is concealed behind the knob 104a itself. In other words, the knob 104a may generate a blind spot region in the indicator 102. In FIG. 7C, which corresponds to FIG. 7A, LED 102a which lights up to indicate the operation amount (LED 102at) is completely within the blind spot region, and cannot be seen by the operator. In FIG. 7D, which corresponds to FIG. 7B, because the operation amount of the knob 104a increases, lit LED 102a is now moved to the LED 102ap. While part of the LED 102ap is out of the blind spot region and is now visible in the example shown in FIG. 7D, such a point of view may change depending on the position of the switch 104, the standing position or physique of the operator, and the like. Therefore, the blind spot region may also change, which would put LED 102at and also LEDs 102a on both sides of LED 102at (i.e., total of three LEDs) completely within the blind spot region, thereby lowering the visibility of the indicator 102. Further, when the attention point as described above is within the blind spot region, there is, of course, a problem that a point which requires particular attention cannot be recognized. Even when such an attention point is located outside the blind spot region, however, there is still a possibility that a change of the point of view makes it difficult to decide whether the operation amount of the switch 104 has exceeded the attention point. The visibility of the indicator 102 is similarly lowered in this case. Thus, there has been a demand that devices allow easy and accurate recognition as to whether indication of the indicator 102 has reached the special indication region indicative of a specific operation amount (such as the blind spot or the attention point) or the state (the indication position) of the indicator 102 in the special indication region. This enhanced visibility of the indicator is especially strongly desired for an operation panel on which a plurality of switches, indicators, and other various instruments are disposed. When it is necessary to simultaneously monitor a plurality of switches, indication lights, indication meters or the like, it is desirable that they can be monitored by moving just the users focus of attention, while minimizing any need to change posture.
Further, when the indicator 102 is placed at a distance from the knob 104a, the problem of the blind spot region as described above can be eliminated. However, an operation panel on which the switch 104, the indicator 102 and other instruments are disposed has a limited space, and formation of an extra space in such a panel will decrease in the number of switches or the like which can be disposed on the panel or increase the size of the operation panel. Also, provision of the switch 104 and the indicator 102 at a distance is not preferable because there is a possibility that the relevance between them will be less recognizable or that their visibility will be decreased.
The present invention was conceived in view of the aforementioned problems of the related art and aims to provide a switch device enabling easy recognition of an operation amount of a switch device with an inexpensive structure and without the need for an operator to change their posture, even when the visibility of the indication of the operation amount by an indicator is obstructed in a special indication region generated as a part of the indicator in the switch device during the indication of the operation amount by the indicator.
In order to achieve the foregoing object, in accordance with one aspect of the present invention, there is provided a switch device comprising an operation knob for a switch; an indicator whose indication state is changed in accordance with an operation amount of the operation knob, the indicator including a special indication region indicating a specific operation amount of said switch and a visible region which is always visible; and a control section for controlling such that the indication state of the indicator is sequentially changed in accordance with the operation amount of the operation knob, the control section changing the indication state in part of the visible region when the change of the indication state of the indicator reaches the special indication region.
Further, in order to achieve the foregoing object, in accordance with another aspect of the present invention, there is provided a switch device comprising an operation knob for a volume switch; an indicator disposed around said operation knob, whose indication state is changed in accordance with an operation amount of the operation knob, the indicator including a special indication region indicating a specific operation amount of said volume switch and a visible region which is always visible; and a control section for controlling such that the indication state of the indicator is sequentially changed in accordance with the operation amount of the operation knob, the control section changing the indication state in part of the visible region when the change of the indication state of the indicator reaches the special indication region.
Here, the indicator may be composed, for example, of a plurality of LEDs, and the control section can control lighting-up of the LEDs in synchronization with the operation amount of the operation knob and also can control lighting-up of the LEDs at arbitrary positions individually. It should be noted that the special indication region and the visible region are determined within a range between the minimum and maximum operation amount of the operation knob.
With the above structure, the fact that lighting-up of the indicator occurs in the special indication region on the indicator or the state of lighting in the special indication region is expressed in the visible region which is easy to recognize. It is therefore possible to recognize the operation amount of the switch indicated in the special indication region with a simple structure.
Further, in accordance with another preferred aspect of the present invention, the special indication region includes a blind spot region in which the indication is obstructed by the operation knob as seen from an operator of the switch device, and said control section changes the indication state of part of the visible region when the change of the indication state of the indicator reaches the blind spot region.
With this structure, even when the portion of the indicator which actually indicates the operation amount of the switch is completely blocked from the operator""s view, such indication state can be expressed in the visible region. Accordingly, the operation amount of the switch which is indicated in the blind spot region can be recognized with a simple structure.
Further, in accordance with another preferred aspect of the present invention, the special indication region includes an attention point indicative of a specific operation state of the switch.
Here, the attention point refers to an operation amount of the switch which requires particular attention, such as a threshold value for the prescribed operation amount, and may represent an appropriate operation amount or an operation neutral point.
With this structure, it is possible to indicate a position which is significant for the switch operation more clearly using the visible region, which enables simple and reliable recognition.
Further, in accordance with another preferred aspect of the present invention, said control section uses the visible region to indicate the indication state of the indicator in the special indication region.
For example, when the special indication region covers a wide range, change within the special indication region can be expressed in the visible region in the same manner, so that the state in the special indication region can be recognized with higher accuracy.
Further, in accordance with another preferred aspect of the present invention, the indication state of part of the visible region is changed by using part of the visible region including end portions when the change of the indication state of the indicator reaches the special indication region.
Because end portions of a region generally have high degree of visibility, improved visibility can be obtained
Further, in accordance with another preferred aspect of the present invention, the indication state of part of the visible region is changed by controlling lighting-up of the indicator at a predetermined position, when the change of the indication state of the indicator reaches the special indication region.
Further, in accordance with another preferred aspect of the present invention, the indication state of part of the visible region is changed by controlling blinking of the indicator at a predetermined position, when the change of the indication state of the indicator reaches the special indication region.
Further, in accordance with another preferred aspect of the present invention, the indication state of part of the visible region is changed by controlling driving of a plurality of elements which constitute the indicator, when the change of the indication state of the indicator reaches the special indication region.
With these structures, the state of the indicator in the special indication region can be expressed in the visible region in a proper and simple manner, so that the visibility can be increased.
Further, in accordance with another preferred aspect of the present invention, the control section causes the indication states of the visible region to vary for each of cases wherein the change of the indication state of the indicator does not reach the attention point after the change reaches the special indication region, wherein the change of the indication state of the indicator reaches the attention point after the change reaches the special indication region, and wherein the change of the indication state of the indicator passes the attention point after the change reaches the special indication region.
For example, before the attention point is reached, an LED in the front side of the visible region is caused to blink or light up. After the attention point is passed, an LED in the passing side of the visible region is caused to blink or light up. When the change of the indication state corresponds exactly to the attention point, the LEDs in both the front and passing sides of the visible region are caused to blink or light up.
With this structure, it is possible to accurately express the actual operation state of the indicator near the attention point using the visible region, thereby increasing the visibility concerning the attention point easily.
It should be noted that while the present invention will be understood more clearly with reference to the preferred embodiment as will be described below, the scope of the present invention is not limited to the following embodiment.